1. Field of the Invention
The present invention pertains to a method for the manufacture of an inductive chip, more especially, an inductive chip of the type with a wire coiled around a core.
2. Description of the Prior Art
Chips include different types of inductive components. Thus, in the prior art, there are inductive chips obtained by screen process printing. Inductive chips may be manufactured by a technique of metallizing a pattern on an insulating substrate or on insulating substrates which are stacked on top of one another and provided with a conductive passage which gives electrical continuity among all the layers. These chips are generally inexpensive and well suited to the needs of manufacturers who make equipment for the general public. However, the chips have inductance values ranging from a few nanohenries to some hundreds of microhenries. Furthermore, their Q factor is quite mediocre and they do not tolerate active currents of more than 100 milliamperes.
There are also inductive chips, known in the prior art, made like the conventional self-inducting coil, by winding an insulated wire, generally made of enamelled copper, around a core made of a material which may or may not be magnetic. These chips cover a wide range of inductance values from a few nanohenries to a few millihenries, and their Q-value is often high. However, the methods used to manufacture components of this type have many disadvantages which result, among other factors, from the small dimensions of the core which makes it difficult to wind the wire. Another constraint is related to the soldering of the ends of the coil to the output connections. This soldering is made difficult by the small dimensions of the core, the diameter of the wire and the presence of the enamel which covers it. All the methods currently used for manufacturing coiled inductive chips consist in winding the wire around the core by making the core rotate around a pin and then, once the coil is made, in connecting the ends of the wire to the output connections or electrodes. The method of making the connection have a certain number of disadvantages. There is a considerable risk of unwinding the wire during subsequent handling. Furthermore, for it to be possible to automate the above methods, the cores on which the wires are wound should have the most exact dimensions possible so that the electrodes can be properly positioned and so that the ends of the coil wire can be soldered to these electrodes.